Thigh fat and muscle each contribute to excess cardiometabolic risk in SouthAsians, independent of visceral adipose tissue

Abstract

ObjectiveTo compare fat distribution and associations between fat depots and cardiometabolic traits in South Asians and Europeans.MethodsFive hundred and fourteen South Asians and 669 Europeans, aged 56-86. Questionnaires, record review, blood testing, and coronary artery calcification scores provided diabetes and clinical plus subclinical coronary heart disease (CHD) diagnoses. Abdominal visceral (VAT) and subcutaneous adipose tissue, thigh subcutaneous adipose tissue (TSAT), intermuscular and intramuscular thigh fat and thigh muscle were measured by CT.ResultsAccounting for body size, South Asians had greater VAT and TSAT than Europeans, but less thigh muscle. Associations between depots and disease were stronger in South Asians than Europeans. In multivariable analyses in South Asians, VAT was positively associated with diabetes and CHD, while TSAT and thigh muscle were protective for diabetes, and thigh muscle for CHD. Differences in VAT and thigh muscle only partially explained the excess diabetes and CHD in South Asians versus Europeans. Insulin resistance did not account for the effects of TSAT or thigh muscle.ConclusionsGreater VAT and TSAT and lesser thigh muscle in South Asians contributed to ethnic differences in cardiometabolic disease. Effects of TSAT and thigh muscle were independent of insulin resistance.

Waist circumference as a vital sign in clinical practice: a Consensus Statement from the IAS and ICCR Working Group on Visceral Obesity

“…For example, in a study of >2,000 older participants from the Health, Ageing and Body Composition study, Marieke Snijder and colleagues were among the first to report that thigh adipose tissue mass is negatively associated with glucose intolerance and dyslipidaemia, after accounting for abdominal adipose tissue mass 47 . This observation was confirmed by Sophie Eastwood and colleagues, who reported that in South Asian adults the protective effects of total subcutaneous adipose tissue for T2DM and HbA 1c levels emerge only after accounting for visceral adipose tissue (VAT) accumulation 48 .…”

“…Alternatively, adults with elevations in BMI for a given waist circumference could have decreased amounts of VAT. Excess lipid accumulation in VAT and ectopic depots is associated with increased cardiometabolic risk [47][48][49] . Moreover, VAT is an established marker of morbidity 50,51 and mortality 24,52 .…”

Changes in Adipose Tissue Depots and Metabolic Markers Following a 1-Year Diet and Exercise Intervention in Overweight and Obese Patients With Type 2 Diabetes

“…Insofar as AT may play a role in IR and different depots may contribute differently to IR or cardiovascular disease (CVD) risk, it is important to establish how various AT depots respond to weight-loss interventions. Most published studies have included a single abdominal slice as a surrogate measure of total VAT or abdominal SAT, but whole-body SAT and whole-body IMAT have rarely been measured (e.g., [ 4 , 5 ]).…”

Measuring body composition and regional fat mass accurately

“…For instance, CT has been used to highlight how visceral AT accumulation is associated with impaired glucose tolerance and reduced insulin sensitivity as well as how the relationship between visceral adiposity and metabolic health differs with respect to gender and ethnicity . Additionally, CT can be used to non‐invasively evaluate hepatic steatosis and measure intramuscular lipid accumulation …”